You will never play Halo on your iPhone. But Gameloft knows you want to, and so it crafted N.O.V.A. to satiate your appetite for a story-driven first-person shooter on the iPhone. Set in a far-flung future where Earth is a wreck and we all live on orbital platforms, you are a bounty hunter that must single-handedly repel an alien invasion. Not necessarily an original yarn, but it neatly ties together a series of incredible, fast-paced stages and firefights against the incoming horde. The controls are among the best in the genre for the iPhone and the level of detail in every stage is astounding (be sure to update it for your iPhone 4). Multiplayer was hot, too, but admittedly that's died down a bit since N.O.V.A. took flight. No matter, the single-player campaign is still one of the great plays on the iPhone and will keep you busy for hours.